80
Table 55 — Economizer Run Status Table
ECONOMIZER DIAGNOSTIC HELP — Because there are
so many conditions which might disable the economizer from
being able to provide free cooling, the control offers a handy
place to identify these potentially disabling sources. All the
user has to do is check ACTV, the "Economizer Active" flag. If
this flag is set to "Yes" there is no reason to explore the group
under DISA, the "Economizer Disabling Conditions." If the
flag is set to "No," this means that at least one or more of the
flags under the group DISA are set to "Yes" and the user can
easily discover exactly what is preventing the economizer from
performing "free cooling."
In addition, the economizer's reported and commanded po-
sitions are viewable as well as one convenient place to view
outside-air temperature, relative humidity, enthalpy and dew
point temperature.
The following information can be found under the local dis-
play mode Run Status
ECON.
Economizer Control Point Determination Logic
— Once the
economizer is allowed to provide free cooling, the economizer
must determine exactly what set point it should try to maintain.
The set point the economizer attempts to maintain when “free
cooling” is located at Run Status
VIEW
EC.C.P. This is
the economizer control point.
The control selects set points differently, based on the
control type of the unit. This control type can be found at
Configuration
UNIT
C.TYP. There are 4 types of control.
C.TYP = 1 VAV-RAT
C.TYP = 2 VAV-SPT
C.TYP = 3 TSTAT Multi-Staging
C.TYP = 4 SPT Multi-Staging
If the economizer is not allowed to do free cooling, then
EC.C.P = 0.
If the economizer is allowed to do free cooling and the
Unoccupied Free Cooling Mode is ON, then EC.C.P =
Setpoints
SASP + Inputs
RSET
SA.S.R.
If the economizer is allowed to do free cooling and the
Dehumidification mode is ON, then EC.C.P = the Cooling
Control Point (Run Status
VIEW
CL.C.P).
NOTE: To check the current cooling stage go to Run Status
Cool
CUR.S.
If the C.TYP is either 1,2,3 or 4, and the unit is in a cool
mode, then EC.C.P = the Cooling Control Point (Run Status
VIEW
CL.C.P).
Building Pressure Control — The N Series Com-
fortLink controller supports several physical rooftop configura-
tions which are used to control building pressure. This section
will describe the various types used. See Table 56.
SETTING UP THE SYSTEM — The building pressure con-
figs are found at the local display under Configuration
BP.
Building Pressure Configuration (
BP.CF) — This configura-
tion selects the type of building pressure control in place
• BP.CF = 0, No building pressure control
• BP.CF = 1, VFD controlling power exhaust to modulate
building pressure control based on building pressure
sensor
• BP.CF = 2, VFD controlling return fan (VFD fan track-
ing)
Building Pressure Sensor (
BP.S) —This configuration allows
the reading of a building pressure sensor when enabled. This
sensor configuration is automatically enabled when BP.CF = 1
or 2.
Building Pressure (+/-) Range (
BP.R) — This configuration
establishes the range in H
2
O that a 4 to 20 mA sensor will be
scaled to. This configuration only allows sensors that measure
both "positive and negative" pressure.
Building Pressure Setpoint (
BP.SP) — This set point is the
building pressure control setpoint. If configured for a type of
modulating building pressure control then this is the set point
that the control will try to clamp or control to.
Building Pressure Setpoint Offset (
BP.SO) — For building
pressure configurations BP.CF=1, this is the offset below the
building pressure set point that the building pressure must fall
below to turn off and disable power exhaust control.
VFD/ Actuator Fire Speed/Pos. (
BP.FS) — For BP.CF = 1
and 2, this configuration is the fire speed override position
when the control is in the purge and evacuation smoke control
modes.
VFD/ Actuator Minimum Speed/Pos. (
BP.MN) — For
BP.CF = 1 and 2, this configuration is the minimum VFD
speed/actuator position during building pressure operation be-
low which the VFD/actuator may not control.
ITEM EXPANSION RANGE UNITS CCN POINT WRITE STATUS
EC1.P Economizer 1 Out Act. Curr. Pos. 0-100 % ECONOPOS
EC2.P Economizer 2 Ret. Act.Curr.Pos. 0-100 % ECON2POS
EC3.P Economizer 3 Out Act.Curr.Pos. 0-100 % ECON3POS
ECN.C Economizer Out Act.Cmd.Pos. 0-100 % ECONOCMD forcible
ACTV Economizer Active ? YES/NO ECACTIVE
DISA ECON DISABLING CONDITIONS
UNV.1 Econ Out Act. Unavailable? YES/NO ECONUNAV
UNV.2 Econ2 Ret Act. Unavailable? YES/NO ECN2UNAV
UNV.3 Econ3 Out Act. Unavailable? YES/NO ECN3UNAV
ENTH Enth. Switch Read High ? YES/NO ENTH
DBC DBC - OAT Lockout? YES/NO DBC_STAT
DEW DEW - OA Dewpt.Lockout? YES/NO DEW_STAT
DDBC DDBD- OAT > RAT Lockout? YES/NO DDBCSTAT
OAEC OAEC- OA Enth Lockout? YES/NO OAECSTAT
DEC DEC - Diff.Enth.Lockout? YES/NO DEC_STAT
EDT EDT Sensor Bad? YES/NO EDT_STAT
OAT OAT Sensor Bad ? YES/NO OAT_STAT
FORC Economizer Forced ? YES/NO ECONFORC
SFON Supply Fan Not On 30s ? YES/NO SFONSTAT
CLOF Cool Mode Not In Effect? YES/NO COOL_OFF
OAQL OAQ Lockout in Effect ? YES/NO OAQLOCKD
HELD Econ Recovery Hold Off? YES/NO ECONHELD
DH.DS Dehumid. Disabled Econ.? YES/NO DHDISABL
O.AIR OUTSIDE AIR INFORMATION
OAT Outside Air Temperature dF OAT forcible
OA.RH Outside Air Rel. Humidity % OARH forcible
OA.E Outside Air Enthalpy OAE
OA.D.T Outside Air Dewpoint Temp dF OADEWTMP
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